Cutting elements are traditionally utilized for a variety of material removal processes, such as machining, cutting, and drilling. For example, tungsten carbide cutting elements have been used for machining metals and on drilling tools for drilling subterranean formations. Similarly, polycrystalline diamond compact (PDC) cutters have been used to machine metals (e.g., non-ferrous metals) and on subterranean drilling tools, such as drill bits, reamers, core bits, and other drilling tools. Other types of cutting elements, such as ceramic (e.g., cubic boron nitride, silicon carbide, and the like) cutting elements or cutting elements formed of other materials have also been utilized for cutting operations.
Drill bit bodies to which cutting elements are attached are often formed of steel or of molded tungsten carbide. Drill bit bodies formed of molded tungsten carbide (so-called matrix-type bit bodies) are typically fabricated by preparing a mold that embodies the inverse of the desired topographic features of the drill bit body to be formed. Tungsten carbide particles are then placed into the mold and a binder material, such as a metal including copper and tin, is melted or infiltrated into the tungsten carbide particles and solidified to form the drill bit body. Steel drill bit bodies, on the other hand, are typically fabricated by machining a piece of steel to form the desired external topographic features of the drill bit body.
In some situations, drill bits employing cutting elements may be used in subterranean mining to drill roof-support holes. For example, in underground mining operations, such as coal mining, tunnels must be formed underground. In order to make the tunnels safe for use, the roofs of the tunnels must be supported in order to reduce the chances of a roof cave-in and/or to block various debris falling from the roof. In order to support a roof in a mine tunnel, boreholes are typically drilled into the roof using a drilling apparatus. The drilling apparatus commonly includes a drill bit attached to a drilling rod (such as a drill steel). Roof bolts are then inserted into the boreholes to anchor a support panel to the roof. The drilled boreholes may be filled with resin prior to inserting the bolts, or the bolts may have self expanding portions, in order to anchor the bolts to the roof.
Various types of cutting elements, such as PDC cutters, have been employed for drilling boreholes for roof bolts. Although other configurations are known in the art, PDC cutters often comprise a substantially cylindrical or semi-cylindrical diamond “table” formed on and bonded under high-pressure and high-temperature (HPHT) conditions to a supporting substrate, such as a cemented tungsten carbide (WC) substrate.
During drilling operations, heat may be generated in the cutting elements due to friction between the cutting elements and a subterranean formation being drilled, causing the drilling equipment to become worn or damaged. Additionally, a significant amount of debris is generated as rock material is fractured and cut away from the subterranean formation by the cutting elements, slowing the drilling process and causing the drilling equipment to become worn or damaged. In order to cool the cutting elements and clear debris away from the cutting area during drilling, a drilling fluid such as drilling mud or air may be pumped into a borehole being drilled. In some examples, the drilling fluid may be pumped through a hole in the drill bit to a fluid port near the cutting elements. In other embodiments, a vacuum may be used to draw material away from the cutting region and to cool the cutting elements.
Ports within drill bits for dispensing drilling fluids may become clogged with debris, such as rock chips, during drilling operations, potentially preventing the drilling fluid from effectively removing debris and cooling the cutting surfaces. Additionally, vacuum ports may become clogged or may lose suction during drilling. For example, there may be insufficient annulus present in a borehole to maintain adequate air flow for removing debris from the cutting area, which may prevent outside air from effectively reaching the vacuum ports. Such problems may cause the drill bits to become worn and damaged due to a lack of adequate cooling and material removal, causing delays in drilling operations. Avoiding such delays may reduce unnecessary downtime and production losses, which may be particularly important during bolting operations in mine tunnels due to various safety hazards present in these environments.